Fine, I'll do it.
I took a picture I remembered had the problem in a particularly severe way. The picture was taken with a Canon 5D, not exactly exotic at the time. This with the process version of LR 4.4:
Original picture, default LR 4 rendering:

Default LR B&W rendering with all cursors to zero:

Branches on the right in the previous photo:

Sky darkened in LR:

Branches on the right in previous picture:

Pinetree trunk and branches:

Sky darkened with Nik Silver Efex Pro as a smart filter in PS:

Branches in previous photo:

Pinetree trunk in previous picture:

So there.